Before the advent of the plastic ski boot in the mid-1960's, all alpine skiers used boots constructed of leather. To provide support, the leather in the lower part of the boot was several layers thick and generally quite stiff. New leather boots required a period of break-in to soften the leather and to improve the comfort of the boots. Once broken-in, leather boots were generally quite comfortable.
In addition to serving as the attachment means between the feet and the skis, the leather boots fulfilled two very important functions. First, the leather boots provided lateral support for the foot, ankle, and lower leg to allow the skier to set an edge for controlling the skis in turns and stops, as well as allowing the skier to hold a position while skiing across slopes. The second important function served by the leather boots was to allow forward and aft flexion of the ankles in all positions between standing upright and the attitude of fully bent ankles.
New leather boots provided good lateral support but were generally painful to the front of the foot during ankle flexion. After a break-in period, the leather at the front of the boot softened and a skier's bending at the ankles became more comfortable while at the same time the boot still provided good lateral support. When the leather had broken-in to this stage, the ski boots were in a condition very acceptable to the skier.
One disadvantage of leather ski boots, however, is that the ski boots continued to soften until the leather was “broken down.” At this stage, the leather became too soft, with a mushiness replacing the necessary lateral support. The excellent ankle flexion characteristics actually improved during this process, but the lateral support became progressively reduced until the ski boots become unusable. As a result, skiers had to periodically replace their leather ski boots, and it was not unusual for athletic skiers to replace their ski boots annually.
The required frequent replacement of leather ski boots was expensive and inconvenient. In the 1960's, rigid plastic ski boots, in particular the Lange plastic boot, were first made available for alpine skiing, and the rigid plastic ski boots were instantly popular. Plastic ski boots provided a superior level of lateral support, and plastic ski boots were generally more durable than leather ski boots in that they did not “break down.” Plastic ski boots hold the foot, ankle, and lower leg more securely than leather ski boots but with the disadvantage that fore and aft flexion of the ankle is severely limited. Most skiers were, however, willing to trade away fore and aft ankle flexion for the greater lateral support featured by plastic ski boots, and the industry moved en-masse to the plastic boot. Within a few years, production of leather boots for alpine skiing was virtually non-existent.
The onset of the rigid plastic ski boot changed the entire skiing paradigm, in some ways for the better and in some ways for the worse. Among the characteristics of plastic alpine ski boots are (1) plastic tends not to become flexible through use, (2) plastic ski boots are more durable and wear better than leather ski boots, (3) plastic ski boots provide superior lateral support for the ankle, and (4) the rigid plastic soles retain their dimensions, which is superior for maintaining the precise settings required for safety release ski bindings. The upper portion of a plastic ski boot has a shell that encompasses the foot. The shell is hard plastic that is integral with the sole and the shell resists deflection because of its rigid construction. The foot has freedom to move only to the extent that the materials in the ski boot between the foot and the shell can compress against the rigid shell. As a result of these characteristics of plastic ski boots, it can be easier for the skier to edge, and skiing on an icy slope is easier. It can also be easier for a skier to maintain control at higher speeds using plastic boots, which can be a desirable characteristic for high speed skiing or racing. In addition, certain maneuvers that depend on good lateral support are easier to perform, for example, skiing on a single ski.
On the other hand, there are disadvantages to using plastic ski boots. Plastic ski boots restrict or entirely prevent flexion of the ankles due to the rigid plastic used, thereby restricting or eliminating the use of the ankles as pivot points, forcing the knees and hip joints to do all the absorption of the forces encountered in skiing. When plastic ski boots were introduced, skiers were required to alter their skiing technique to cope with the lack of flexion of the ankles.
Moreover, in some respects, plastic boots have too much lateral support. It is difficult, for example, not to edge, i.e., to flatten the ski against the slope, rather than dig into the slope with the edges. To flatten the skis against a slope, a wearer of plastic ski boots must usually move his knees to one side, rather than simply relax his ankles. Skiing techniques that require quick turns with the skis flattened, for example the Austrian wedel, are impossible or are accomplished with great difficulty when wearing plastic ski boots.
In contrast, leather alpine ski boots do not have a hard shell encompassing the foot and the material of the upper portion is never integral with the sole. A foot in a leather ski boot has greater freedom for small amounts of movement because of the slight deflections of the shell-less upper portion, adding comfort to the wearer. In addition, leather alpine ski boots have the following characteristics: (1) leather ski boots allow superior fore and aft ankle flexion, (2) a skier using leather boots has three pivot points (the hips, the knees, and the ankles) for absorbing the shocks and forces inherent in skiing, (3) the additional pivot at the ankles permits a skier with average ability to ski much more smoothly than is possible with plastic boots, and (4) the fact that leather ski boots have less lateral support than plastic ski boots also contributes to a skier's ability to execute a number of maneuvers in a more stylish manner.
Taken together, the superior ankle flexion and the slightly reduced lateral support of leather ski boots, as compared to plastic boots, give a skier several advantages:                a. It is easier for the skier to ski with his feet together.        b. It is easier for the skier to maintain his back in an erect position.        c. It is easier for the skier to ski with his weight over his skis, not forward or aft.        d. It is easier for the skier to release an edge and to ski with the skis flat on the snow if desired.        e. It is easier for the skier to execute such stylish techniques from the 1950's as the Austrian wedel.        
While leather ski boots provide certain advantages, there are certain characteristics of leather ski boots that are disadvantageous. For example, leather ski boots have a relatively short life as compared to plastic ski boots. As discussed above, the lateral support of leather ski boots becomes reduced as the boots are flexed in normal use, and when the lateral support becomes insufficient for the purposes of the skier, the boot is deemed broken-down or worn out. Indeed, the lateral support of leather boots is always less than that of plastic boots and therefore provides less control for the skier in icy conditions and is inferior for maintaining control at high speeds.
Another disadvantage of leather ski boots is the soles of leather ski boots do not conform to the requirements of ISO 5355, Alpine Ski-Boots—Safety Requirements and Test Methods, the international standard that specifies the dimensions and tolerances for the soles of alpine ski boots so that they are compatible with modern ski bindings.
The technique of one's alpine skiing should be a personal matter but it is in reality dictated by the equipment that is available in the marketplace. For those who would choose to ski utilizing techniques that were prevalent prior to the advent of the plastic ski boot, it would be advantageous to choose a modern boot that included the best features from the leather ski boot era. Accordingly, it is an object of the present invention to provide alpine ski boots that feature little or no restriction to the fore and aft flexion of the ankles, while providing lateral support to the ankles, and that can meet the requirements of international standards for design to ensure compatibility with modern safety release bindings for alpine skis.